Sydney businessman Ron Medich arrives at Central Local Court for the start of his committal hearing.

ABC News: Thomas Oriti

A committal hearing involving two men charged over the killing of Sydney businessman Michael McGurk has been bogged down by legal argument.

Property developer Ron Medich has appeared at Sydney's Central Local Court court charged over the killing of Mr McGurk, who was shot in the head outside his home on Sydney's north shore in September 2009.

Medich is accused of masterminding the killing and Christopher Estephan, who was 19 at the time, is charged with carrying out the act.

Former boxer Lucky Gattellari has already been sentenced for his role in the killing and is expected to give evidence to the hearing.

Medich's barrister Winston Terracini SC is seeking a non-publication order on proceedings before Gattellari appears.

He argued evidence from other witnesses could taint what the former boxer says in court.

The court heard Gattellari could now appear as early as Monday.

Media outlets are expected to challenge the non-publication order if Magistrate Jan Stevenson allows it tomorrow morning.

The committal hearing involves 75 volumes of evidence and is expected to last six weeks.